Two serum pancreatic isoamylase determinations compared

Serum pancreatic isoamylase activity was measured by a method involving inhibition of salivary isoamylase and by a well-known agarose electrophoretic method, modified by us. We saw changes in electrophoretic patterns of pancreatic isoamylase fractions after storage of serum samples for three weeks at 4-8 degrees C, but with the inhibition method no alterations in activities were found. Within-assay and between-assay imprecisions of both methods were about the same. Serum pancreatic amylase activities as measured by the inhibition method exceeded by about 10% those obtained by the electrophoretic method. The inhibition method seems to be a reasonable candidate for routine application, whereas the electrophoretic method is still time-consuming and requires special skill to perform. Some suggestions are given for improving the calibration of the inhibition method recommended by the manufacturer.